Modular element for reverse osmosis filtering devices

ABSTRACT

A modular element for making reverse osmosis filtering devices includes: at least one first container and a second container, each of which is provided with a tubular lateral wall, with a bottom plate which closes a first axial end of said lateral wall, with an inlet, with a first outlet and with a second outlet, the first and second containers being arranged so that the respective lateral walls are arranged adjacent and have mutually parallel central axes, and a scavenging duct which connects the second outlet of the first container with the inlet of the second container, the first container, the second container and the scavenging duct are obtained as a single monolithic body.

TECHNICAL FIELD

The present invention generally relates to reverse osmosis filteringdevices. More particularly, the present invention relates to a modularelement that can be used in the modular construction of the aforesaidfiltering devices.

PRIOR ART

As is known, in reverse osmosis filtering devices, the water to betreated is fed into a pressure container in which an osmotic membranefiltering cartridge is accommodated. The osmotic membrane is suitable toallow the selective passage of a part of water (permeate) but not of allthe salts possibly dissolved therein, which are therefore concentratedin the reject water that remains upstream of the filtering cartridge.

In particular, said filtering devices exploit the principle ofcross-flow filtration, since the reject water with the highestconcentration of salts that remains upstream of the filtering cartridgeis continuously discharged from the pressure container, to prevent thesalts and/or other pollutants from being able to quickly clog theosmotic membrane.

From the plant engineering point of view, the pressure container inwhich the filtering cartridge is accommodated is therefore generallyprovided with an inlet for the water to be filtered, with a first outletfor the filtered water (permeate) with a low concentration of salts andwith a second outlet for discharging the reject water with a highconcentration of salts.

In order for this type of filtering device not to discharge an excessiveamount of reject water, it is generally necessary that the water to befiltered remains inside the pressure container for a relatively longtime, i.e. that the flow rate of the reject water is relatively low.

On the other hand, the longer the residence time of the water to befiltered inside the pressure container, the greater the possibility thatsalts and/or other pollutants are deposited on the osmotic membrane ofthe filtering cartridge, causing it to clog.

For this reason, the flow rate of reject water that is discharged fromthe pressure container is normally quite relevant.

To solve this drawback, filtering devices have been proposed whichcomprise at least two osmotic membrane filtering cartridges, which areinserted in respective pressure containers connected hydraulically inseries with each other, i.e. in which the first outlet of the firstpressure container is hydraulically connected with the inlet of thesecond container. In this way, the reject water exiting the firstpressure container is conveyed directly into the second pressurecontainer, where it is filtered again by the corresponding osmoticmembrane filtering cartridge, obtaining an overall higher flow rate offiltered water (permeate) and a lower flow rate of reject water.

However, the hydraulic connection between the first and the secondpressure container currently requires the use of various hoses andfittings which, added to the numerous hoses and fittings that arealready present inside the filtering device, for example those carryingthe water to be filtered and discharging the reject water, considerablycomplicate the architecture of the filtering device, increasing itsoverall dimensions and causing numerous other functional problems.

For example, the large number of hoses and fittings entails a largenumber of points in which water leaks can be generated as a result ofbreakages due, for example, to the ageing of the components and to thevibrations to which they are subjected during operation.

The high hydraulic complexity also involves that each maintenanceintervention can be very slow and complicated, due to the difficulty ofidentifying, among all the hoses and fittings present, those that havebeen damaged, to the point that these maintenance interventions mustoften be carried out by extremely experienced personnel who know thefiltering device in every detail.

Finally, the large number of hoses and fittings entails a significantincrease in pressure drops and a multiplication of potential waterstagnation points, which can become a source of bacterial proliferationand/or favour the sedimentation of salts and/or other impurities.

DISCLOSURE OF THE INVENTION

In light of the foregoing, an object of the present invention is toreduce or at least to mitigate the aforementioned drawbacks of the knownart, within the framework of a simple, compact solution with a ratherlow installation and maintenance cost.

These and other objects are reached thanks to the characteristics of theinvention as set forth in the independent claim 1. The dependent claimsoutline preferred and/or particularly advantageous aspects of theinvention.

In particular, an embodiment of the present invention makes available amodular element for making reverse osmosis filtering devices,comprising:

-   -   at least a first container and a second container, each of which        is provided with a tubular lateral wall, with a bottom plate        which closes a first axial end of said lateral wall, with an        inlet, with a first outlet and with a second outlet, said first        and second container being arranged so that the respective        lateral walls are arranged adjacent and have mutually parallel        central axes, and    -   a scavenging duct which connects the second outlet of the first        container with the inlet of the second container,

wherein said first container, said second container and said scavengingduct are obtained as a single monolithic body.

Thanks to said monolithic body, it is advantageously possible to make areverse osmosis filtering device provided with two containers that arealready hydraulically connected in series, with no need to use all thehoses and fittings of the prior art, increasing the compactness of thefiltering device and the simplicity thereof, and consequently reducingpotential breaking points, potential stagnation points and pressuredrops, to the advantage of productivity and ease of maintenance.

According to an aspect of the present invention, the first outlet ofeach of said first and second container can be obtained in thecorresponding bottom plate, while the inlet and the second outlet ofeach of said first and second container can be obtained in thecorresponding lateral wall, on the side facing towards the lateral wallof the other container.

In this way the monolithic body in which all these elements areintegrated is more compact and easier to make.

In particular, the inlet and the second outlet of each of said first andsecond container can have axes perpendicular to the central axes of thelateral walls of the first and of the second container and can lie inthe same plane on which the central axes of said lateral walls lie.

According to another aspect of the invention, the monolithic body canfurther comprise two connection ducts, which are positioned in aninterspace comprised between the lateral walls of the first and of thesecond container and wherein the axes are straight and orthogonal to theplane on which the central axes of said lateral walls lie.

A first of said connection ducts can be placed in hydrauliccommunication with the inlet of the first container while a second ofsaid connection ducts can be placed in hydraulic communication with thesecond outlet of the second container.

Each of said first and second connection duct can also have two oppositeaxial ends which project on opposite sides with respect to the plane onwhich the central axes of the lateral walls of the first and of thesecond container lie.

Thanks to this solution, the monolithic bodies of two or more modularelements can be advantageously coupled together, in an extremely simpleand rapid way, composing a reverse osmosis filtering device whichcomprises multiple pairs of containers, wherein the containers of eachpair are mutually connected in series while the pairs are connectedbetween them in parallel.

In this way it is possible to increase the overall flow rate of filteredwater at the outlet, while remaining within a very compact solution andwith a reduced number of hoses and fittings.

A further and preferred aspect of the invention provides that themonolithic body can also comprise a collection manifold communicatingboth with the first outlet of the first container and with the firstoutlet of the second container and provided with an outlet mouth.

Thanks to this solution, the modular element also integrates a manifoldfor the collection of the permeate that outflows from both containersplaced in series, further reducing the number of fittings and hydraulicconnections necessary for making the reverse osmosis filtering device.

According to another aspect of the invention, the monolithic body cancomprise a third connection duct having axis straight and orthogonal tothe plane on which the central axes of the lateral walls of the firstand of the second container, which intersects the collection manifoldand has two opposite free ends projecting from opposite sides of thecollection manifold lie.

In this way, the collection manifolds of all the modular elements thatmake up the filtering device can be advantageously connected to eachother through respective third connection ducts, allowing to obtain asingle outlet point of filtered water (permeate), always remainingwithin the scope of a very simple solution and with a very small numberof hoses and fittings.

Another aspect of the present invention provides that a bypass openingwhich places the internal volume of the first container in communicationwith the collection manifold is obtained in the bottom plate of thefirst container, a valve being provided for closing and/or adjusting theopening degree of said bypass opening.

Thanks to this solution, it is advantageously possible to mix part ofthe reject water present inside the first container with the filteredwater (permeate) that is collected in the collection manifold, forexample in order to adjust the salinity of the water that it is suppliedat the outlet from the reverse osmosis filtering device.

Another aspect of the invention provides that the monolithic body cancomprise one or more fixing bushings, each of which is positioned in theinterspace comprised between the lateral walls of the first and of thesecond container and has axis orthogonal to the plane on which thecentral axes of said lateral walls lie.

Said fixing bushings can be advantageously used to fix together, forexample by means of threaded tie rods and bolts, the monolithic bodiesof a plurality of modular elements, or to fix other components of thereverse osmosis filtering device to said monolithic bodies.

The monolithic body can also comprise a plurality of positioning tangsderiving from the lateral walls of the first and of the second containerwith axes perpendicular to the plane on which the central axes of thelateral walls lie, and a plurality of positioning pins also derivingfrom the lateral walls of the first and of the second container, each ofwhich is coaxial to a corresponding positioning tang but it is obtainedon the opposite side of the latter with respect to the plane on whichthe central axes of the lateral walls lie.

In this way, when two modular elements are assembled together, it isadvantageously possible to align the positioning tangs of one with thepositioning pins of the other one and to couple them together, optimallyorienting the respective monolithic bodies before fixing them together.

According to another aspect of the invention, the monolithic body canfurther comprise at least two fixing plates lying in the plane on whichthe central axes of the lateral walls of the first and of the secondcontainer lie, each of which derives from the lateral wall of arespective container from the opposite side with respect to the othercontainer.

Said fixing plates can be advantageously inserted into correspondingslits which can be made in a support structure of the reverse osmosisfiltering device, so as to lock two or more modular elements betweenthem, with no the need to use the self-tapping screws mentionedpreviously.

According to a further aspect of the invention, the modular element canof course also comprise two osmotic membrane filtering cartridges, eachof which is inserted into a respective of said first and secondcontainer, for partitioning the internal volume thereof into threechambers, including a first chamber placed in communication with theinlet, a second chamber placed in communication with the first outletand a third chamber placed in communication with the second outlet.

BRIEF DESCRIPTION OF THE FIGURES

Further features and advantages of the invention will be more apparentafter reading the following description provided by way of non-limitingexample, with the aid of the figures illustrated in the accompanyingdrawings.

FIG. 1 is a perspective view of a water treatment plant according to anembodiment of the present invention, without the external case.

FIG. 2 is a section of the plant of FIG. 1 made according to the planeII-II indicated in FIG. 3.

FIG. 3 is the section III-III of FIG. 2, shown on an enlarged scale.

FIG. 3A is an enlarged detail of FIG. 3 showing the closing system ofthe containers.

FIG. 3B is the section IIIB-IIIB indicated in FIG. 3A.

FIG. 4 is the section IV-IV of FIG. 2, shown on an enlarged scale.

FIG. 5 is the section V-V of FIG. 2 shown on an enlarged scale.

FIG. 6 is the section VI-VI of FIG. 2, shown on an enlarged scale.

FIG. 7 is the section VII-VII of FIG. 2, shown on an enlarged scale.

FIG. 8 is section VIII-VIII of Figure/shown on a reduced scale.

FIG. 8A is an enlarged detail of FIG. 8 showing the outlet module.

FIG. 9 is a perspective view of a water treatment plant according to analternative embodiment of the present invention.

FIG. 10 is a side view of the plant of FIG. 9.

FIG. 11 is the section XI-XI of FIG. 10, shown on an enlarged scale.

FIG. 12 is the section XII-XII of FIG. 10, shown on an enlarged scale.

FIG. 13 is the section XIII-XIII of FIG. 12 shown on a reduced scale.

FIG. 14 is a bottom view of the plant of FIG. 9.

FIG. 15 is a top view of the plant of FIG. 9.

FIG. 16 is a partially exploded perspective view of a modular elementused in the osmotic action filtering device of the plants of FIGS. 1 and9.

FIG. 17 is a perspective view of a monolithic body that makes up themodular element of FIG. 16.

FIG. 18 is a side view of a pumping group used in the plants of FIGS. 1and 9.

FIG. 19 is the section XIX-XIX of FIG. 18.

FIG. 20 is a perspective view of an outlet module used in the plants ofFIGS. 1 and 9.

FIG. 21 is an exploded view of the outlet module of FIG. 20.

FIG. 22 is a partially exploded perspective view of a filtering devicefor mechanical separation used in the plant of FIG. 1.

FIG. 23 is another perspective and partially exploded view of thefiltering device of FIG. 22 shown from another angle.

FIG. 24 is a front view of a filtering device for mechanical separationof the independent type which can be used for example in associationwith the plant of FIG. 9.

FIG. 25 is the section XXV-XXV of FIG. 24.

FIG. 26 is the section XXVI-XXVI of FIG. 25, shown on an enlarged scale.

FIG. 27 is the section of FIG. 26 shown with the main componentsseparated along the direction of mutual coupling.

FIG. 28 is section XXVIII-XXVIII of FIG. 26 shown on a reduced scale.

FIGS. 29, 30 and 31 are a partially exploded perspective view of thefiltering device of FIG. 24 shown in as many steps during the assemblyprocess.

FIGS. 32, 33 and 34 are the same views of FIGS. 29, 30 and 31 in whichthe filtering device has been sectioned along the plane XXV-XXV of FIG.24.

FIG. 35 is a simplified hydraulic diagram of a reverse osmosis filteringdevice belonging to the plant illustrated in FIGS. 1 to 8.

FIG. 36 is a simplified hydraulic diagram of a reverse osmosis filteringdevice belonging to the plant illustrated in FIGS. 9 to 15.

DETAILED DESCRIPTION

The aforesaid figures describe two examples of a plant 100 for thetreatment of water, which can be advantageously used both in the foodsector, for example for the treatment of water intended for directconsumption or for the preparation of beverages or other foods, and inthe technological field, for example for the treatment of water intendedfor washing plants (e.g. dishwashers, washing machines or other), andfor applications that can be both for domestic and industrial use.

Both plants 100 schematically comprise an inlet duct 101 for the waterto be treated, which can be connected for example with the waterdistribution network, an outlet duct 102 for the treated water, whichcan be connected with the utilities, and a discharge duct 103 for anyreject water, which can be connected, for example, with a sewer disposalsystem.

According to an aspect of the present disclosure, the outlet duct 102can be integrated into a more complex outlet module 600, which comprisesnumerous other functions of the plant 100 in order to limit theconnections with pipes and fittings.

The plant 100 also comprises a pumping group 200, which is suitable toreceive water coming from the inlet duct 101 and to feed it underpressure towards the outlet ducts 102 and discharge ducts 103, afterhaving made it pass through the treatment devices.

The inlet duct 101 can be provided with a main solenoid valve 104, whichis suitable to be controlled by an electronic control unit (notillustrated) to selectively allow or prevent the inflow of water towardsthe pumping group 200.

The inlet duct 101 can also be provided with a bypass solenoid valve105, which is normally closed and can be controlled for its opening inorder to place the inlet duct 101 in direct communication with theoutlet duct 102, regardless of the opening or closing state of the mainsolenoid valve 104.

In particular, the bypass solenoid valve 105 can be controlled by theelectronic control unit which also controls the main solenoid valve 104or by a simple switch which allows the selective feeding of theelectronic control unit or of the bypass solenoid valve 105.

Between the pumping group 200 and the outlet ducts 102 and dischargeducts 103, the plant 100 can comprise a first filtering device 300,which is generally designed to retain the coarse particles andimpurities that may be present in water and possibly to retain chlorineand/or other substances which may be present in water so as to eliminateor at least reduce the bacterial load.

The first filtering device 300 can be configured to perform a mechanicalfiltration and/or a filtration by adsorption of chemicals, for exampleby means of activated carbon. In addition or alternatively, the firstfiltering device 300 can contain resins which can also work by ionexchange, in order to advantageously replace some salts that arecontained in the water with other salts. Depending on the type of resinchosen, said resins can operate in many different ways, for example butnot exclusively by replacing carbonates with sodium chloride, in orderto lower the hardness of water without reducing the fixed residuethereof.

The plant 100 can also comprise a second reverse osmosis filteringdevice 400, which is suitable to receive the water filtered from thefirst filtering device 300 and is mainly designed to remove the saltsthat can be dissolved in the water.

As illustrated in the example of FIG. 9, in some embodiments, the firstfiltering device 300 may be absent and may possibly be made in the formof a separate device (see FIG. 24) which is positioned for exampleupstream of the plant 100, i.e. which is suitable to receive the waterto be filtered from the water network and which, after filtering it,feeds it to the inlet duct 101 of the plant 100 or to any other utility.

Starting from this general scheme, the various parts of the plant 100are detailed below starting from the reverse osmosis filtering device400.

Reverse Osmosis Filtering Device

The reverse osmosis filtering device 400 comprises one or more modularelements 401, substantially identical or in any case similar, which canbe advantageously assembled together to vary the operative capacity ofthe reverse osmosis filtering device 400, for example the hourly flowrate of filterable water, based on the specific needs and requirementsof the utilities to which the plant 100 is intended.

As illustrated in FIG. 16, each modular element 401 comprises amonolithic body 402, which can be made of plastic, for example by meansof the injection molding technique. In particular, the monolithic body402 can be directly obtained as a single piece, or it can be obtained inseveral parts which are then inseparably joined together, for example bywelding or gluing, thus forming a single piece.

The monolithic body 402 comprises (defines) a first container 403 and asecond container 404, each of which is substantially shaped like avessel comprising a tubular-shaped lateral wall 405, for examplecylindrical, and a bottom plate 406, for example with a rounded shape,which closes a first axial end of the lateral wall 405.

The second and opposite axial end of each of said first and secondcontainer 403 and 404 is closed by a respective closing system 500 ofthe openable type, which will be described in detail below.

As clearly visible in FIG. 3, the first and the second container 403 and404 are preferably arranged so that the respective lateral walls 405 arearranged adjacent to each other and have respective mutually parallelcentral axes A and B.

Preferably, the lateral walls 405 of the first and of the secondcontainer 403 and 404 are not in mutual contact but are separated by asmall interspace 407.

Furthermore, the lateral walls 405 of the first and of the secondcontainer 403 and 404 preferably have the same length, i.e. the samelongitudinal extension, and bring the respective bottom plates 406substantially to the same axial level with respect to the central axes Aand B.

In particular, the first and the second container 403 and 404 areintended to be installed in such a way that the central axes A and B ofthe corresponding lateral walls 405 are oriented vertically and that thebottom plates 406 are positioned at the bottom, each of them for closingthe lower axial end of the corresponding lateral wall 405.

Remaining on FIG. 3, the first container 403 comprises an inlet 408 forthe water to be filtered, a first outlet 409 for the filtered water anda second outlet 410 for the reject water.

Preferably, the inlet 408 and the second outlet 410 are obtained in thelateral wall 405 of the first container 403, for example both in thepart facing towards the lateral wall 405 of the second container 404.

In particular, the inlet 408 and the second outlet 410 can have mutuallyparallel axes, perpendicular to the central axes A and B of the lateralwalls 405 of the first and of the second container 403 and 404, and bothlying in the same plane on which said central axes A and B lie.

The distance between the inlet 408 and the bottom plate 406 of the firstcontainer 403 is generally greater than the distance between said bottomplate 406 and the second outlet 410.

However, both the inlet 408 and the second outlet 410 can be closer tothe axial end of the lateral wall 405 in which the corresponding closingsystem 500 is placed than to the axial end in which the correspondingbottom plate 406 is placed.

The first outlet 409 can be obtained in the bottom plate 406 of thefirst container 403, for example with axis coinciding with the centralaxis A of the lateral wall 405 of the first container 403 itself.

Inside the first container 403 an osmotic membrane filtering cartridge411 can be accommodated, which is generally suitable to partition theinternal volume of the first container 403 into three separate chambers,of which a first chamber 412 placed in communication with the inlet 408,a second chamber 413 placed in communication with the first outlet 409,and a third chamber 460 placed in communication with the second outlet410.

The osmotic membrane filtering cartridge 411 is known per se andgenerally comprises a central support tube 414, which is internallyhollow and has a perforated lateral wall.

The osmotic membrane filtering cartridge 411 further comprises one ormore pockets, which are spirally wound around the central support tube414 forming a sort of cylindrical coil 415.

Each of said pockets is substantially formed by two sheets of osmoticmembrane, which are at least slightly spaced apart from each other,defining a thin interspace.

In order to create the interspace between the pockets and inside them, asort of mesh is used, called spacer or tricot.

The pockets are associated with the central support tube 414 so that theaforesaid interspaces are placed in communication with the holesobtained in the lateral wall of the central support tube 414, isolatingthem from the surrounding environment.

The osmotic membrane filtering cartridge 411 can further comprise anannular gasket 416, which can be coaxially associated externally to thecylindrical coil 415.

The osmotic membrane filtering cartridge 411 is coaxially insertedinside the first container 403, so that a terminal segment of thecentral support tube 414 is inserted, by interposition of suitablesealing gaskets, into the first outlet 409.

In this way, the internal volume of the central support tube 414practically defines the second chamber 413.

The annular gasket 416, on the other hand, is suitable for sealingbetween the outer surface of the cylindrical coil 415 and the innersurface of the lateral wall 405 of the first container 403, preferablyin a segment axially comprised between the inlet 408 and the secondoutlet 410, partitioning the first chamber 412 from the third chamber460.

In this way, the water coming from the inlet 408 can flow freely outsidethe pockets of the osmotic membrane filtering cartridge 411 until itreaches the second outlet 410.

However, by virtue of the fact that in the first container 403 there isa pressure level higher than the osmotic pressure, part of the water intransit is able to cross the osmotic membrane sheets and reach theinterspace defined between them, and then flow through the internalcavity of the central support tube 414 towards the first outlet 409.

Thanks to the reverse osmosis phenomenon, starting from a water at theinlet having a certain concentration of salts, the filtered water thatoutflows from the first outlet 409 will have a significantly lowerconcentration of salts than the reject water that reaches the secondoutlet 410.

The second container 404 in turn comprises an inlet 417 for the water tobe filtered, a first outlet 418 for the filtered water and a secondoutlet 419 for the reject water.

Preferably, the inlet 417 and the second outlet 419 are obtained in thelateral wall 405 of the second container 404, for example both in thepart facing towards the lateral wall 405 of the first container 403.

In particular, the inlet 417 and the second outlet 419 can have mutuallyparallel axes, perpendicular to the central axes A and B of the lateralwalls 405 of the first and of the second container 403 and 404, and bothlying in the same plane on which said central axes A and B lie.

The distance between the inlet 417 and the bottom plate 406 of thesecond container 404 is generally greater than the distance between saidbottom plate 406 and the second outlet 419.

However, while the second outlet 419 may be closer to the correspondingbottom plate 406 than to the corresponding closing system 500, the inlet417 may be closer to the corresponding closing system 500 than to thecorresponding bottom plate 406.

For example, with respect to the direction defined by the central axes Aand B of the lateral walls 405 of the first and of the second container403 and 404, the inlet 417 of the second container 404 can be positionedbetween the inlet 408 and the second outlet 410 of the first container403, while the second outlet 419 of the second container 404 can bepositioned between the second outlet 410 of the first container 403 andthe bottom plates 406.

Also in this case, the first outlet 418 can be obtained in the bottomplate 406 of the second container 404, for example with axis coincidingwith the axis B of the lateral wall 405 of the second container 404itself.

Inside the second container 404, a further osmotic membrane filteringcartridge 420 can be accommodated, which is generally suitable topartition the internal volume of the second container 404 into threeseparate chambers, of which a first chamber 421 placed in communicationwith the inlet 417, a second chamber 422 placed in communication withthe first outlet 418, and a third chamber 461 placed in communicationwith the second outlet 419.

The osmotic membrane filtering cartridge 420 is completely similar tothe osmotic membrane filtering cartridge 411 described previously, ofwhich it has the same characteristics.

The osmotic membrane filtering cartridge 420 is therefore coaxiallyinserted into the second container 404, in such a way that a terminalsegment of the central support tube 414 is inserted, by interposition ofsuitable sealing gaskets, into the first outlet 418.

The annular gasket 416 is suitable for sealing between the outer surfaceof the cylindrical coil 415 and the inner surface of the lateral wall405 of the second container 404, preferably in a segment axiallycomprised between the inlet 417 and the second outlet 419.

In this way, the water coming from the inlet 417 can flow freelyexternally to the pockets of the osmotic membrane filtering cartridge420 until it reaches the second outlet 419 but, by virtue of the factthat a pressure level higher than the osmotic pressure reigns in thesecond container 404, part of this water is able to cross the osmoticmembrane sheets and reach the internal cavity of the central supporttube 414 and then flow towards the first outlet 418.

Also in this case, the reverse osmosis phenomenon ensures that startingfrom a water at the inlet having a certain concentration of salts, thefiltered water that outflows from the first outlet 418 has asignificantly lower concentration of said salts than the reject waterreaching the second outlet 419.

According to an important aspect of the modular element 401, themonolithic body 402 also comprises a scavenging duct 423 which connectsthe second outlet 410 of the first container 403 with the inlet 417 ofthe second container 404, so that the reject water exiting from thefirst container 403 becomes the water to be filtered in the secondcontainer 404.

In other words, this solution entails that the first and the secondcontainer 403 and 404 are hydraulically connected between them inseries, allowing the water coming from the inlet 408 of the firstcontainer 403 to be filtered in cascade by two osmotic membranefiltering cartridges 411 and 420, thus producing two flows of filteredwater through the first outlets 409 and 418 of the first and of thesecond container 403 and 404 and a single flow of reject water throughthe second outlet 419 of the second container 404.

It is wished to observe here that, in order to ensure that a pressurehigher than the osmotic pressure reigns inside the first container 403and the second container 404, the plant 100 generally comprises a flowrestrictor, which is connected downstream of the second outlet 419 ofthe second container 404, as will be described later.

Returning to the scavenging duct 423, this duct can be obtained in aportion of the monolithic body 402 which extends into the interspace 407between the first and the second container 403 and 404, connecting therespective lateral walls 405.

The scavenging duct 423 can be defined by a hole extending in adirection parallel to the central axes A and B of the lateral walls 405and which can lead outwards at the closing systems 500, where it can beoccluded by a suitable plug 424.

This hole can also be placed in communication with the inlet 408 of thefirst container 403, which is however hydraulically separated from thescavenging duct 423 by a shutter insert 425 which is inserted into thehole, at a level comprised between the inlet 408 of the first container403 and the inlet 417 of the second container 404.

The monolithic body 402 of each modular element 401 can further comprise(define) a collection manifold 426, which is placed in communicationwith both the first outlets 409 and 418 of the first and of the secondcontainer 403 and 404, so as to collect the filtered water.

The collection manifold 426 can be directly joined to the bottom plates406, for example on the opposite side with respect to the lateral walls405 of the first and of the second container 403 and 404.

The collection manifold 426 can be shaped as a duct, for example astraight duct, the central axis C of which is oriented perpendicularlyto the central axes A and B of the lateral walls 405 of the first and ofthe second container 403 and 404, however lying preferably in the sameplane on which said central axes A and B lie.

The collection manifold 426 is provided with an outlet mouth 427,through which the filtered water can be conveyed towards the firstoutlet duct 102 of the plant 100.

This outlet mouth 427 can have axis straight, for example coincidingwith the central axis A of the lateral wall 405 of the first container403, facing on the opposite side with respect to the correspondingbottom plate 406.

The collection manifold 426 can also be placed in direct communicationwith the first chamber 412 of the first container 403, for examplethrough a bypass opening 428 which can be obtained in the bottom plate406 of the first container 403 and which can lead out at a first axialend of the collection manifold 426.

In this way, part of the reject water (with a higher concentration ofsalts) present in the first container 403 can be mixed with the filteredwater found in the collection manifold 426, in order to adjust theeffective salinity of the water that is supplied to utilities.

This expedient can be particularly useful when water is used in thepreparation of beverages, for example to feed automatic coffee machinesor the like, in order to ensure a correct flavour of the beverage.

For said mixing to be adjusted, the collection manifold 426 can beequipped with a valve 429, for example a needle and manually operatedvalve, which is screwed to the end of the collection manifold 426 andwhich, based on the axial position thereof, is suitable for closingand/or adjusting the opening degree of the bypass opening 428.

The opposite axial end of the collection manifold duct 426 can insteadbe simply closed by means of a plug 430.

Switching now to FIG. 4, it can be observed how the monolithic body 402of each modular element 401 can comprise a first connection duct 431,which is positioned in the interspace 407 comprised between the firstand the second container 403 and 404 and is hydraulically placed incommunication with the inlet 408 of the first container 403.

In particular, said first connection duct 431 can have axis straight andorthogonal to the plane of lying which contains the central axes A and Bof the first and of the second container 403 and 404.

Furthermore, the first connection duct 431 can extend from both sides ofthe aforesaid lying plane, so as to have an intermediate segment placedin communication with the inlet 408 of the first container 403 and twoopposite axial, open and free projecting ends.

For example, the first connection duct 431 can be obtained in the sameportion of the monolithic body 402 in which the scavenging duct 423 isalso obtained.

In particular, the first connection duct 431 can intersect the holedefining the scavenging duct 423 and be separated from the latter by thealready mentioned shutter insert 425.

As illustrated in FIG. 6, the monolithic body 402 of each modularelement 401 also comprises a second connection duct 432, which is alsopositioned in the interspace 407 comprised between the first and thesecond container 403 and 404 but is hydraulically placed incommunication with the second outlet 419 of the second container 404.

This second connection duct 432 can also have axis straight andorthogonal to the plane of lying which contains the central axes A and Bof the first and of the second container 403 and 404.

Furthermore, the second connection duct 432 can also extend from bothsides of the aforesaid lying plane, so as to have an intermediatesegment placed in communication with the second outlet 419 of the secondcontainer 404 and two opposite axial open and free projecting ends.

For example, the second connection duct 432 can have substantially thesame length as the first connection duct 431 and be perfectly alignedwith the latter, along the direction defined by the central axes A and Bof the first and of the second container 403 and 404.

As illustrated in FIG. 7, the monolithic body 402 of each modularelement 401 can finally also comprise a third connection duct 433, whichsubstantially intersects and is hydraulically placed in communicationwith the collection manifold 426.

In particular, said third connection duct 433 can have axis straight andparallel to the axes of the first and of the second connection duct 431and 432 but can be arranged offset with respect to the latter, forexample positioned so as to intersect the central axis A of the lateralwall 405 of the first container 403.

The third connection duct 433 can also extend from both sides of thelying plane which contains the central axes A and B of the first and ofthe second container 403 and 404, so as to have an intermediate segmentplaced in communication with (which intersects) the collection manifold426 and two opposite axial ends projecting from opposite sides of thecollection manifold 426, which are open and free.

In the embodiment illustrated in FIGS. 1 to 8, the reverse osmosisfiltering device 400 comprises two of the modular elements 401 describedabove, which are connected between them so as to operate in parallel.

In particular, the two modular elements 401 are arranged so that thefirst connection duct 431, the second connection duct 432 and the thirdconnection duct 433 of each of them are coaxially aligned respectivelywith the first connection duct 431, with the second connection duct 432and with the third connection duct 433 of the other modular element 401.

As illustrated in FIG. 4, the first connection ducts 431 of the twomodular elements 401 can be hydraulically connected by means of aconnecting sleeve 434, preferably rigid and straight, the opposite endsof which can be inserted, preferably by interposition of annular sealinggaskets, on the free ends of the two first connection ducts 431 whichare proximal to each other.

With regard to the distal ends of the first two connection ducts 431,one of them can be occluded by a plug 435 while the other one can beconnected so as to receive the water to be filtered.

In this way, the two first connection ducts 431 and the relativeconnecting sleeve 434 substantially define an inlet manifold whichdistributes the water to be filtered into the inlets 408 of the firstcontainers 403 of both modular elements 401.

Similarly (see FIG. 6), the second connection ducts 432 of the twomodular elements 401 can be hydraulically connected by means of aconnecting sleeve 436, preferably similar to the previous one, theopposite ends of which can be inserted, preferably by interposition ofannular sealing gaskets, on the free ends of the two second connectionducts 432 which are proximal to each other.

The distal end of one of the second connection ducts 432 can be occludedby a plug 437, while the distal end of the other connection duct 432 canbe hydraulically connected directly to the discharge duct 103 of theplant 100.

In this way, the two second connection ducts 432 and the relativeconnecting sleeve 436 substantially define a discharge manifold whichcollects the reject water coming from the second outlets 419 of thesecond containers 404 of both the modular elements 401 and conveys ittowards the discharge duct 103.

To ensure that a pressure higher than the osmotic pressure reigns insidethe first and the second container 403 and 404 of each modular element401, the discharge duct 103 can contain the already mentioned flowrestrictor 109.

As illustrated in FIG. 2, the flow restrictor 109 can be configured as anarrowing of the opening section of the discharge duct 103 and canoptionally be of an adjustable type, i.e. it can allow a variation inthe extent of such narrowing in order to suitably vary the pressureinside the first and the second container 403 and 404 of each modularelement 401.

Inside the discharge duct 103 there may also be a non-return valve 110,which can be positioned downstream of the flow restrictor 109 withrespect to the direction of exit of the reject water.

Said non-return valve 110 is oriented so as to allow the reject water tooutflow towards the exit, while preventing instead the opposite path.

Referring now to FIG. 7, it can be observed that also the thirdconnection ducts 433 of the two modular elements 401 can behydraulically connected by means of a connecting sleeve 438, preferablysimilar to the previous ones, the opposite ends of which can beinserted, preferably by interposition of annular sealing gaskets, on thefree ends of the two third connection ducts 433 which are proximal toeach other.

Both distal ends of the two third connection ducts 433 can be singularlyoccluded by a plug 439.

In this way, the two third connection ducts 433 and the relativeconnecting sleeve 438 place the collection manifolds 426 of both modularelements 401 in hydraulic communication, so as to convey all thefiltered water towards the outlet duct 102 of the plant 100.

In particular, since the outlet duct 102 can be only one, it can beconnected to the outlet mouth 427 of only one of the modular elements401, while the outlet mouth 427 of the other modular element 401 can beoccluded with a plug.

It is wished to highlight that, in other embodiments, the connectionbetween the modular elements 401 could take place without connectingsleeves 434 and/or 436 and/or 438, for example by shaping the firstconnection ducts 431 and/or the second connection ducts 432 and/or thethird connection ducts 433 so that they integrate themselves male/femalecouplings with relative seals, i.e. said male/female couplings areobtained as an integral part of the relative monolithic body 402.

As illustrated in FIG. 1, in order to facilitate the assembly of themodular elements 401, the monolithic body 402 of each of them cancomprise a plurality of positioning tangs 440 (see also FIGS. 16 and 17)deriving from the lateral walls 405 of the first and of the secondcontainer 403 and 404 with axes perpendicular to the plane on which thecentral axes A and B of said lateral walls 405 lie, as well as aplurality of positioning pins 441 also deriving from the lateral walls405 of the first and of the second container 403 and 404, each of whichis coaxial to a corresponding positioning tang 440 but it is obtained onthe opposite side with respect to the lying plane of the central axes Aand B of the lateral walls 405.

In this way, when the monolithic bodies 402 of two modular elements 401are assembled together, the positioning pins 441 of one of saidmonolithic bodies 402 can be singularly aligned and coaxially coupled tothe positioning tangs 440 of the other monolithic body 402, ensuringperfect alignment also of the first, of the second and of the thirdconnection ducts 431, 432 and 433.

To stably fix the modular elements 401 between them, each monolithicbody 402 can further comprise one or more fixing bushings 442, hollowinside, each of which can be positioned in the interspace 407 comprisedbetween the lateral walls 405 of the first and of the second container403 and 404, where it can extend with axis orthogonal to the plane onwhich the central axes A and B of said lateral walls 405 lie.

For example, in the embodiment illustrated in the figures, themonolithic body 402 of the modular elements 401 comprises two fixingbushings 442 positioned between the first connection duct 431 and thesecond connection duct 432.

When the monolithic bodies 402 of two modular elements 401 are assembledtogether, each fixing bushing 442 of one of said monolithic bodies 402is coaxially aligned with a corresponding fixing bushing 442 of theother monolithic body 402, as illustrated in FIG. 2.

A cylindrical spacer 443 can optionally be interposed between a fixingbushing 442 of a modular element 401 and the corresponding fixingbushing 442 of the other modular element 401 and, inside their cavities,a threaded tie rod can be inserted which is fixed with a nut so as tokeep the modular elements 401 axially locked.

Alternatively or in addition, the locking of the modular elements 401can be obtained thanks to a shape coupling between them and acorresponding support structure.

In this regard (see FIG. 17), the monolithic body 402 of each modularelement 401 can comprise, for example, two fixing plates lying in theplane on which the central axes A and B of the first and of the secondcontainer 403 and 404 lie, of which a first fixing plate 444 deriving ina cantilever fashion from the lateral wall 405 of the first container403, on the opposite side with respect to the second container 404, anda second fixing plate 445 deriving in a cantilever fashion from thelateral wall 405 of the second container 404, on the opposite side withrespect to the first container 403.

Each of said fixing plates 444 and 445 can extend as a profile with asubstantially constant section along a direction parallel to the centralaxes A and B of the first and of the second container 403 and 404.

For example, the section of each of said fixing plates 444 and 445 cansubstantially have a T shape.

As illustrated in FIG. 5, the support structure can be fixed for exampleinside a protective case that encloses the plant 100 and can comprisetwo flat walls 446 mutually parallel and facing each other, which areseparated by a distance substantially equal to the distance between thefixing plates 444 and 445 of each modular element 401.

Each of said flat walls 446 can have a plurality of slits 447 whichextend parallel to each other, for example extending in a verticaldirection.

Each slit 447 of a flat wall 446 can face a corresponding slit 447 ofthe flat wall 446, opposite with respect to a direction orthogonal tothe flat walls 446 themselves.

The distance between two consecutive slits 447 of the same flat wall 446can be substantially equal to the distance that separates the fixingplates 444 and/or 445 of two modular elements 401 assembled together aspreviously described.

In this way, after having assembled the two modular elements 401, theycan be inserted into the space comprised between the two flat walls 446,by inserting the fixing plates 444 and 445 of each modular element 401into a pair of mutually opposite slits 447 of the two flat walls 446,which thus lock the modular elements 401 in the assembly position withno the need for screws or bolts.

To better understand the operation of this embodiment, reference can bemade to FIG. 35, which shows the simplified hydraulic diagram of thereverse osmosis filtering device illustrated in FIGS. 1 to 8.

The water coming from the pumping group 200 is fed in parallel to theinlets 408 of the first containers 403 of both modular elements 401.

The water crossing the osmotic membrane filtering cartridge 411contained in each of said first containers 403 flows through the firstoutlets 409 directly into the collection manifold 426 towards the outletduct 102.

The reject water exiting from the second outlet 410 of each of the firstcontainers 403 instead flows in the scavenging duct 423 towards theinlet 417 of the corresponding second container 404.

The water crossing the osmotic filtering cartridge 420 contained in eachof the second containers 403 also flows through the first outlets 418 inthe collection manifold 426 towards the outlet duct 102, while thereject water which finally outflows from the second outlets 419 flowsthrough the flow restrictor 109 towards the discharge duct 103.

In this way, the two modular elements 401 are hydraulically connected inparallel to each other, while the first and the second container 403 and404 of each modular element are hydraulically connected in series.

Thanks to the connection in series, water can flow faster, makingcross-flow filtration more efficient and therefore allowing lessconcentrate to be discarded.

By exploiting this modularity principle, other embodiments may providethat the reverse osmosis filtering device 400 comprises a greater numberof modular elements 401, assembled together in the same fashionillustrated previously.

Other embodiments, such as the one illustrated in FIG. 9, can alsoprovide that the reverse osmosis filtering device 400 comprises a singlemodular element 401.

In this case, the modular element 401 is substantially similar to theone described above, the only difference being that the third connectionduct 433 has both free ends occluded by a plug 448 (see FIG. 11), thatthe first connection duct 431 has a free end suitable to be connectedfor receiving the water to be filtered and an opposite free end occludedby a plug 449 (see FIG. 12), and that the second connection duct 432 hasa free end occluded by a plug 450 and an opposite free end connected tothe discharge duct 103.

Also in this embodiment, the discharge duct 103 can be provided with theflow restrictor 109 and with the non-return valve 110, as previouslydescribed with reference to FIG. 2.

The simplified hydraulic scheme of this second embodiment is illustratedin FIG. 36, in which it can be appreciated how the water coming from thepumping group 200 is fed to the inlet 408 of the first container 403 ofthe single modular element 401.

The water crossing the osmotic membrane filtering cartridge 411contained in the first container 403 flows through the first outlet 409directly in the collection manifold 426 towards the outlet duct 102,while the reject water exiting the second outlet 410 of the firstcontainer 403 flows in the scavenging duct 423 towards the inlet 417 ofthe second container 404.

At this point, the water crossing the osmotic filtering cartridge 420contained in the second container 403 also flows through the firstoutlet 418 in the collection manifold 426 towards the outlet duct 102,while the last reject water that outflows from the second outlet 419flows through the flow restrictor 109 towards the discharge duct 103.

Also in this case, thanks to the connection in series, the water canflow faster, making the cross-flow filtration more efficient andtherefore allowing less concentrate to be discarded. It is wished topoint out here that the modular elements 401 used in the embodimentsdescribed above can all be identical to each other but could also beslightly different, while remaining conceptually very similar. Forexample, it is possible to provide versions in which one or more of theconnection ducts, instead of being closed by plugs as described above,can have ends which are obtained already closed, for example in themolding step of the monolithic body 402.

Closing System of the Containers

As previously mentioned, both the first and the second container 403 and404 of each modular element 401 are closed, on the opposite side withrespect to the bottom plate 406, by a respective closing system 500.

Said closing system 500, which is the same for both containers 403 and404, is configured so as to allow selective opening of the container,for example to replace the corresponding osmotic membrane filteringcartridge 411 or 420.

In the following, the closing system 500 will be described withreference to the first container 403 but the same considerations applymutatis mutandis also to the closing system 500 of the second container404.

With particular reference to FIGS. 3A, 3B and 16, it can be observedthat the closing system 500 comprises an occlusion element 501, which issuitable to be coupled to the second end of the lateral wall 405 of thefirst container 403, i.e. the one opposite the bottom plate 406,preferably without any type of threaded connection.

Said occlusion element 501 has a cylindrical lower portion 502 suitableto be coaxially inserted into the second end of the lateral wall 405 ofthe first container 403.

One or more annular seats 503 are coaxially obtained on the outerlateral surface of said cylindrical portion 502, each of which issuitable to accommodate an annular gasket 504. Although in the drawingsthe annular seats 503 have a substantially “C”-shaped cross section,i.e. with three closed sides and only one open side facing outwards, itis not excluded that in other embodiments the annular seats 503 may havea cross section with a substantially “L” shape, i.e. with two closedsides and two open sides facing outwards and in axial directionrespectively.

The annular gaskets 504 are singularly designed to obtain a radialsealing between the outer lateral surface of the cylindrical portion 502of the occlusion element 501 and the inner surface of the lateral wall405 of the first container 403.

In particular, it should be observed that the cylindrical portion 502 isinternally hollow and is substantially defined by a tubular wall 505having a first axial end closed by a transverse wall 506, and a secondand opposite open axial end, which faces the inside of the firstcontainer 403 towards the corresponding bottom plate 406.

In this way, the transverse wall 506 occludes the internal volume of thefirst container 403 while the cavity delimited by the tubular wall 505faces towards the bottom plate 406.

Preferably, the tubular wall 505 has a thickness (in a radial directionwith respect to the axis of the cylindrical portion 502) which, at leastin the area of mutual insertion, is smaller than the thickness of thelateral wall 405 of the first container 403 (in a radial direction withrespect to the central axis A).

In this way, following the overpressure that reigns inside the firstcontainer 403 during the operation of the plant 100, the tubular wall505 of the occlusion element 501 tends to expand radially outwards, morethan the lateral wall 405 of the first container 403, resulting in theincrease in the radial compression of the annular gaskets 504, to theadvantage of the seal.

The occlusion element 501 further comprises an upper portion 507, whichis suitable to remain external to the first container 403, projectingaxially beyond the open end of the lateral wall 405, on the oppositeside with respect to the bottom plate 406.

Said upper portion 507 can be obtained as a single body with the lowercylindrical portion 502 and can also have a shape substantiallycylindrical and coaxial with the cylindrical portion 502 itself.

From the lateral surface of the upper portion 507 one or more abutmentelements 508 project radially in a cantilever fashion outwards, whichare suitable to rest axially on the edge of the second axial end of thelateral wall 405 of the first container 403, so as to limit the axialposition of the cylindrical portion 502 in the insertion direction.

In the illustrated embodiment, the abutment elements 508 can be arrangedangularly equidistant with respect to the axis of the lower cylindricalportion 502.

According to an advantageous aspect of the present solution (see alsoFIG. 17), the edge of the second axial end of the first container 403 isnot perfectly flat, i.e. it does not lie in a single plane orthogonal tothe central axis A of the lateral wall 405, but it has circumferentiallyan alternation of depressions 509 and rises 510 that are mutuallyconnected by means of inclined surfaces, in which the axial distancebetween the bottom of the depressions 509 and the bottom plate 406 issmaller than the axial distance between the bottom plate 406 and the topof the rises 510.

For example, the edge of the second axial end of the first container 403can comprise a number of depressions 509 (and therefore of rises 510)equal to the number of abutment elements 508 of the occlusion element501 and which can be distributed in the same way, for example angularlyequidistant with respect to the central axis A of the lateral wall 405.

In this way, when the abutment elements 508 rest on the bottom of thedepressions 509, the cylindrical lower portion 502 of the occlusionelement 501 is at the maximum insertion degree inside the firstcontainer 403, in an operative position in which all annular gaskets 504ensure an effective sealing.

If the occlusion element 501 is rotated around the central axis A of thefirst container 403, starting from the aforesaid operative position, theabutment elements 508 slide on the inclined surfaces which connect thedepressions 509 to the rises 510, causing a progressive and contextualslipping off of the lower cylindrical portion 502.

In other words, the shaped edge of the second axial end of the lateralwall 405 defines a cam profile on which the abutment elements 508 of theocclusion element 501 can slide, following a rotation of the latteraround the central axis A, and which is suitable to transform saidrotation into an axial displacement of the occlusion element 501 withrespect to the lateral wall 405.

This solution is advantageous because, during the operation of thereverse osmosis filtering device 400, the annular gaskets 504 tend toadhere (stick) to the inner lateral surface of the lateral wall 405,potentially making a purely axial extraction of the occlusion element501 difficult.

Thanks to the cam system described above, the combined action ofrotation and translation facilitates the detachment of the annulargaskets 504, making it easier to remove the occlusion element 501.

Furthermore, the release is less traumatic as it is progressive andalways with coaxial movement, unlike a free and uncontrolled traction.

To facilitate the rotation of the occlusion element 501, the upperportion 507 can comprise an axial cavity 511, facing towards the outsideof the first container 403, which is suitable to obtain a prismaticcoupling with a maneuvering key 512 of the coupled type.

In the illustrated embodiment, the axial cavity 511 is made as acylindrical cavity, from the inner surface of which one or more radialribs 513 project.

The manoeuvring key 512 in turn comprises a cylindrical tang 514suitable to be coaxially inserted, preferably to size, into the axialcavity 511, which is provided with one or more slits 515 suitable toreceive the radial ribs 513, making in this way the manoeuvring key 512integral in rotation with the occlusion element 501.

However, it is not excluded that, in other embodiments, the prismaticcoupling between the manoeuvring key 512 and the axial cavity 511 of theocclusion element 501 can be obtained with completely different shapesand/or methods.

Still with a view to facilitating the rotation of the occlusion element501 during the removal step, for example if the manoeuvring key 512 wasnot available, the upper portion 507 of the occlusion element 501 cancomprise one or more through slots 516 having axes oriented transversely(for example orthogonal) with respect to the axis of the cylindricalportion 502.

Said through slots 516 can be obtained in the lateral wall that delimitsthe axial cavity 511, for example at and above the abutment elements508, and can be diametrically aligned two by two, so that each pair ofaligned through slots 516 substantially defines a single aperture whichcompletely crosses the upper portion 507 of the occlusion element 501.

In this way, the removal of the occlusion element 501 can be made byinserting any elongated tool, for example a screwdriver, into a pair ofthrough slots 516, and by using the lever provided by said tool, torotate the occlusion element 501 and slide it on the cam profile.

It is wished to underline here that the latter tool, as well as themanoeuvring key 512 described above, are accessories which can besupplied and used to remove the occlusion element 501 but which are notpart of the closing system 500.

The closing system 500, on the other hand, further comprises atightening member 517, the sole function of which is to axially lock theocclusion element 501 in the operative position in which the abutmentelements 508 rest in the depressions 509, supporting the axial pressureforces being unloaded on it.

This tightening member 517 comprises a ring nut 518, for example withsubstantially cylindrical shape, which is suitable to surround theocclusion element 501 and to be coaxially screwed external to the secondaxial end of the lateral wall 405 of the first container 403.

The tightening member 517 further comprises at least one abutmentsurface 519 suitable to rest on the upper portion 507 of the occlusionelement 501, when the same is in the operative position.

For example, the abutment surface 519 can be defined by a bottom wall520 which for example completely occludes an axial end of the ring nut518, giving the tightening member 517 substantially the shape of acover.

Since it only needs to provide an axial constraint against the slippingoff of the occlusion element 501, the tightening member 517 does notcarry any type of gasket and does not have to be tightly screwed to thefirst container 403.

Nevertheless, it is obviously preferable that the tightening member 517cannot unscrew freely, for example following the vibrations caused bythe operation of the plant.

For this reason, the closing system 500 can comprise an anti-unscrewingsystem which prevents the tightening member 517 from unscrewing withrespect to the lateral wall 405 of the first container 403.

This anti-unscrewing system can comprise a first notch 521 firmly fixedto the tightening member 517, for example which projects axially in acantilever fashion from the edge of the ring nut 518 on the oppositeside with respect to the bottom wall 520 (see FIG. 16).

In this way, by screwing and unscrewing the tightening member 517, thefirst notch 521 is suitable to vary its own axial distance with respectto the second edge of the lateral wall 405 of the first container 403,up to a maximum value that is reached when the tightening member 517 iscompletely screwed down.

The anti-unscrewing system can further comprise a second notch 522,which is instead coupled to the lateral wall 405 of the first container403, so as to be able to move between an engagement position and adisengagement position.

In particular, the second notch 522 can be carried by a slider 523,which is slidingly coupled to a guide 524 obtained in the lateral wall405 of the first container 403, for example aligned with the fixingplate 444 and between the latter and the second end of the lateral wall405.

The slider 523, being coupled with this guide 524, can be suitable toslide in a direction parallel to the central axis A of the lateral wall405, so that, when it is in the engagement position, the second notch522 is closer to the second end of lateral wall 405 with respect to whenit is in the disengagement position.

In particular, when it is in the engagement position, the second notch522 is placed at a distance from the second end of the lateral wall 405which is equal to or smaller than the distance reached by the firstnotch 521, when the tightening member 517 is completely screwed down,while when it is in the disengagement position, the second notch 522 isplaced at a distance from the second end of the lateral wall 405 whichis greater than the distance reached by the first notch 521.

In this way, by bringing the second tooth 522 into the disengagementposition, it is advantageously possible to freely unscrew and screwagain the tightening member 517.

By instead bringing the second notch 522 into the engagement position,for example after the complete screwing of the tightening member 517,the second notch 522 interferes with the first notch 521, preventingaccidental unscrewing of the tightening member 517.

A spring 525 (see FIG. 3A) can be interposed between the slider 523 andthe relative guide 524, so as to push and keep the second notch 522normally in the engagement position.

It is wished to point out here that, although in the example illustratedthe ring nut 518 is a threaded ring nut which is coaxially screwed tothe external of the second axial end of the lateral wall 405 of thefirst container 403, it is not excluded that, in other embodiments, thering nut 518 can be axially constrained to the lateral wall 405 of thefirst container 403 by other means of mutual coupling, for example bymeans of a bayonet coupling or other.

Pumping Group

As anticipated in the introduction, the plant 100 can comprise a pumpinggroup 200, which is suitable to receive the water coming from the inletduct 101 and to feed it under pressure towards the reverse osmosisfiltering device 400, possibly after having made it transit through themechanical separation filtering device 300.

With particular reference to FIGS. 18 and 19, the pumping group 200comprises a pump 201, for example a vane pump, which is provided with aninlet 202 for low-pressure water and with an outlet 203 forhigh-pressure water, and a motor 204, for example an electric motor,which is coupled to the pump 201 in order to drive it.

The pumping group 200 may further comprise a liquid cooling system forthe motor 204.

This cooling system comprises a tubular manifold 205, substantiallyshaped as a straight duct having a central axis D, which comprises aninlet terminal 206 and an outlet terminal 207, positioned at apredetermined mutual distance, with respect to the direction defined bythe axis central D of the tubular manifold 205.

The cooling system further comprises a branch pipe 208, which is woundas a coil around the motor 204 and has a first end 209 and a secondopposite end 210.

Both the first and the second end 209 and 210 of the branch pipe 208 arehydraulically connected to the tubular manifold 205, in a portioncomprised between the inlet terminal 206 and the outlet terminal 207.

The first and the second end 209 and 210 of the branch pipe 208 are alsopositioned at a predetermined mutual distance, with respect to thedirection defined by the axis D of the tubular manifold 205.

For example, the first end 209 is placed at a distance from the inletterminal 206 which is smaller than the distance between said inletterminal 206 and the second end 210, which can instead be closer to theoutlet terminal 207.

Preferably, the diameter of the branch pipe 208 is smaller than thediameter of the tubular manifold 205, while the overall length thereofcan be greater than the length Lc of the entire segment of the tubularmanifold 205 which is comprised between the first and the second end 209and 210 of branch pipe 208.

In the embodiments illustrated in FIGS. 1 and 9, the inlet terminal 206of the tubular manifold 205 is suitable to be connected with the inletduct 101 of the plant 100, for example through the main solenoid valve104, so as to be able to receive the water to be treated directly, forexample the one coming from the water network.

The outlet terminal 207 of the tubular manifold 205 is instead connectedto the inlet 202 of the pump 201, the outlet 203 of which can beconnected to the reverse osmosis filtering device 400, possibly throughthe mechanical separation filtering device 300 (if any).

In this way, the tubular manifold 205 of the cooling system ishydraulically connected in series with the pump 201 and upstream of thelatter with respect to the water direction.

In other embodiments, while remaining hydraulically connected in series,the tubular manifold 205 of the cooling system could nevertheless beconnected downstream of the pump 201 with respect to the waterdirection.

In this case, the inlet 202 of the pump 201 could be directly connectedwith the inlet duct 101 of the plant 100, for example through the mainsolenoid valve 104, while the outlet 203 of the pump 201 could beconnected with the inlet terminal 206 of the tubular manifold 205, theoutlet terminal 207 of which could be connected to the reverse osmosisfiltering device 400, possibly through the mechanical separationfiltering device 300 (if any).

In both cases, when the pump 201 is running and the main solenoid valve104 is open, the tubular manifold 205 of the cooling system is traversedby the water that will be treated in the plant 100.

In addition to further travelling along the tubular manifold 205, fromthe inlet terminal 206 towards the outlet terminal 207, part of thiswater is also diverted and flows inside the branch pipe 208, placingitself in a heat exchange relationship with the motor 204.

In this way, the water circulating in the branch pipe 208 subtracts partof the heat produced by the motor 204, cooling it effectively, beforejoining again the portion of water that flows only in the tubularmanifold 205 and continuing together towards the filtrating devices.

On the other hand, since not all the water traverses the branch pipe 208but a substantial part thereof travels only along the tubular manifold205, from the inlet terminal 206 towards the outlet terminal 207, thissolution allows to keep pressure drops rather low.

Naturally, to maximize the cooling of the motor 204 while minimizing thepressure drop, the various parts of the cooling system must be sizedappropriately.

Purely by way of example, a rough sizing of the cooling system is shown,assuming to use a 360 W motor 204 with 60% efficiency and admitting anincrease in temperature DT of the water in the branch pipe 208 equal to5° C.

To remove this heat (considering the specific heat of water and assumingpejoratively the total transfer of the heat to water), it can becalculated that the branch pipe 218 must be traversed by a water flowrate of at least 0.4 liters/minute.

To meet this requirement, the cooling system can be made using a tubularcollector 205 having an intermediate segment length Lc=100 mm and apressure drop coefficient in turbulent flow Kc=0.0011 (experimentalvalue based on the pipe used), and using a branch pipe 208 with overalllength Ls=2500 mm and a pressure drop coefficient in turbulent flowKs=0.0077 (experimental value based on the pipe used).

As proof of this, it can be considered that, in turbulent flow, thepressure drop P in a duct is proportional to the length L of the duct,to the pressure drop coefficient K and to the square of the flow rate Q.

Since the branch pipe 208 joins again the tubular manifold 205, thepressure drop P of said two ducts must be the same, from which itfollows that the following relationship must be satisfied:

Ks*Ls*Qs ² =Kc*Lc*Qc ²

where Qs is the flow rate along the branch pipe 208 while Qc is the flowrate along the intermediate segment of the tubular manifold 205.

By inserting the previous values in this relationship, it is obtainedthat:

Qc/Qs=13.2

Considering that the pump 201 is able to produce a total flow rate equalto Qc+Qs=16 liters/minute, it can be obtained that the flow rate alongthe intermediate segment of the tubular manifold 205 is equal to Qc=14.9liters/minute, while the flow rate along the branch pipe 208 is equal toQs=1.1 liters/minute, that is, well above the minimum of 0.4liters/minute, required for cooling the motor 204 under the previoushypotheses.

In general terms, it can be stated that it is preferable that thetubular manifold 205 and the branch pipe 208 are sized so that the flowof water traversing the tubular manifold 205 is greater than the flow ofwater traversing the branch pipe 208.

In particular, it is preferable that the sizing is such that the flowrate of water flowing along the tubular manifold 205 is equal to orgreater than 70% of the total water flow rate entering the coolingsystem and that only the remaining portion, equal or less than 30%,flows along the branch pipe 208.

In analytical terms, it is therefore preferable that the pressure dropcoefficients Ks and Kc and the lengths Ls and Lc, respectively of thebranch pipe 208 and of the tubular manifold 205, are chosen so as torespect the following condition:

$\frac{Qc}{Qs} = {{\frac{Ks*Ls}{Kc*Lc} \geq \frac{70}{30}} = {{2.3}33}}$

First Filtering Device

The mechanical separation filtering device 300 schematically includes afiltering group 301 and a fixed support element 302, to which thefiltering group 301 is preferably associated in a removable way, forexample in order to allow the replacement thereof when necessary.

As anticipated in the introduction, the filtering device 300 can beinserted into the plant 100 or it can be obtained as a separate entity.

However, since the filtering device 300 has substantially the samecharacteristics in both cases, it will be described below with referencemainly to the case in which it is a separate entity, it being understoodthat the same considerations also apply in the case in which thefiltering device 300 is integrated into the plant 100, and vice versa.

As illustrated in FIG. 29, the filtering group 301 comprises an externalcasing comprising a cup-like body 303 and a cover 304 suitable to closesaid cup-like body 303.

The cup-like body 303 is generally provided with a lateral wall 305 withtubular shape, for example cylindrical, which has a predeterminedcentral axis E, and a bottom plate 306 positioned so as to close a firstaxial end of said lateral wall 305.

The second and opposite axial end of the lateral wall 305 is closed bythe cover 304, which can for example be screwed to the external to thelateral wall 305 preferably by interposition of at least one annularsealing gasket.

The cover 304 is provided with an inlet duct 307 for the water to befiltered and with an outlet duct 308 for the filtered water.

As illustrated in FIG. 25, a filtering cartridge 309 is accommodatedinside the cup-like body 303, for example but not necessarily afiltering cartridge with a substantially tubular shape, which partitionsthe internal volume of the cup-like body 303 into a first chamber 310,which is placed in communication with the inlet duct 307 (see FIG. 28),and a second chamber 311, which is placed in communication with theoutlet duct 308.

In this way, the water crossing the outer casing from the inlet duct 307towards the outlet duct 308 is forced to cross the filtering cartridge309.

The filtering cartridge 309 generally comprises a filtering medium,which is suitable to be crossed by water in order to perform theintended filtration function.

This filtering medium can comprise a porous or perforated body, withmeshes of suitable size, which allows to retain by mechanical action thecoarse particles and/or other solid impurities that may be presentinside water, in order to prevent them from reaching the reverse osmosisfiltering device 400, where they could damage the osmotic membranefiltering cartridges 411 and 420.

Alternatively or in addition, the filtering medium of the filteringcartridge 309 can comprise activated carbon, for example in the form offlakes or granules, which, being crossed by water, may be able to absorband/or retain chlorine and/or by chemical interaction and/or otherunwanted chemicals that may be present in water.

Alternatively or in addition, the filtering medium of the filteringcartridge 309 can comprise resins, usually but not necessarily in theform of spheroidal granules, which can also work by ion exchange, inorder to advantageously replace some salts that are contained in waterwith other salts. Depending on the type of resin chosen, said resins canoperate in many different ways, for example but not exclusively byreplacing carbonates with sodium chloride, in order to lower thehardness of water without reducing the fixed residue thereof.

In some embodiments, the filtering medium can simply be constituted byactivated carbon, for example in the form of flakes or granules, or byresins, for example in the form of spheroidal granules, which are loadeddirectly into the cup-like body 303.

Returning to the inlet and outlet ducts 307 and 308, it can be observedin FIG. 28 that the inlet duct 307 comprises a connecting segment 312,directly communicating with the first chamber 310 of the cup-like body303, which rises from the cover 304 with axis straight, parallel andpreferably offset with respect to the central axis E of the lateral wall305 (see also FIG. 27).

The inlet duct 307 also comprises a terminal segment 313 deriving in acantilever fashion from the connecting segment 312 and extending withaxis F straight and orthogonal to the central axis E, so as to lead outto the outside of the cup-like body 303 for receiving the water to befiltered.

Similarly, it can be observed in FIG. 25 that the outlet duct 308comprises a connecting segment 314, directly communicating with thesecond chamber 311 of the cup-like body 303, which rises from the cover304 with axis straight, parallel and preferably coinciding with thecentral axis E of the lateral wall 305.

The outlet duct 308 also comprises a terminal segment 315 deriving in acantilever fashion from the connecting segment 314 and extending withaxis G straight and orthogonal to the central axis E, so as to lead outto the outside of the cup-like body 303 for allowing the outflow of thefiltered water.

As illustrated in FIG. 27, the terminal segment 315 of the outlet duct308 is arranged adjacent, oriented parallel to and facing in the samedirection as the terminal segment 313 of the inlet duct 307.

For example, the axes F and G of the terminal segments 313 and 315 canlie coplanar on a plane orthogonal to the axis E of the lateral wall 305of the cup-like body 303.

Furthermore, the free ends of the terminal segments 313 and 315, i.e.those afferent directly to the outside, can be placed at the samedistance with respect to a plane orthogonal to the axes F and G andpassing through the central axis E of the lateral wall 305.

As already mentioned, the filtering group 301 is suitable to beassociated in a removable way with the corresponding fixed supportelement 302, for example in order to be replaced when necessary.

In all the embodiments of the filtering device 300, the support element302 is provided with a first connection duct 317 and with a secondconnection duct 318, each of which comprises a free terminal segment,indicated respectively with 319 and 320.

As illustrated in FIG. 27, the terminal segments 319 and 320 of theconnection ducts 317 and 318 are mutually arranged adjacent, haveparallel axes (for example horizontal) and are oriented in the samedirection, substantially specular to the terminal segments 313 and 315of the inlet and outlet ducts 307 and 308 of the filtering group 301.

In this way, the terminal segment 313 of the inlet duct 307 of thefiltering group 301 can be coaxially coupled with terminal segment 319of the first connection duct 317 and, at the same time, the terminalsegment 315 of the outlet duct 308 of the filtering group 301 can becoaxially coupled with the terminal segment 320 of the second connectionduct 318.

In particular, said coaxial couplings can take place by inserting theterminal segments 313 and 315 of the inlet 307 and outlet 308 duct ofthe filtering group 301 inside the corresponding terminal segments 319and 320 of the first and of the second connection ducts 317 and 318, asillustrated in FIG. 26.

To ensure the sealing of said couplings, a respective annular sealinggasket 321 can be coaxially interposed between each terminal segment 319and 320 of the first and of the second connection duct 317 and 318 andthe corresponding terminal segment 313 and 315 of the inlet duct 307 andof the outlet duct 308 of the filtering group 301.

Said annular gaskets 321 are preferably mounted coaxially inside theterminal segments 319 and 320 of the first and of the second connectionduct 317 and 318, where each of them can be axially locked by means of arespective ring nut 322 fixed to the end of the respective terminalsegment 319 and 320.

In this way, the two annular gaskets 321 remain constantly associatedwith the fixed support element 302, while the filtering group 301, whichrepresents the replaceable part of the filtering device 300, isadvantageously simpler and therefore more economical.

The ring nut 322 can be a ring nut that can be inserted by pressure lock(clip) and which can possibly be removed by rotation, for example formaintenance interventions.

To facilitate the coupling and uncoupling of the filtering group 301with respect to the support element 302, the filtering device 400 cancomprise a coupling and guide system suitable to constrain the filteringgroup 301 to the support element 302 in a configuration in which theaxes F and G of the terminal segments 313 and 315 of the inlet duct 307and of the outlet duct 308 of the filtering group 301 coinciderespectively with the axis of the terminal segment 319 of the firstconnection duct 317 and with the axis of the terminal segment 320 of thesecond connection duct 318.

By maintaining this configuration, the coupling and guide system alsoallows the filtering group 301 to slide with respect to the supportelement 302 along a sliding direction parallel to the axes F and G ofsaid terminal segments 313 and 315 of the inlet duct 307 and of theoutlet duct 308, favouring the coupling and the uncoupling thereof.

As illustrated in FIG. 1, said coupling and guide system may comprisefor example a plate 323 fixed to the cover 304 of the filtering group301 and having at least two lateral edges 324 oriented parallel to theaxes F and G of the terminal segments 313 and 315 of the inlet duct 307and of the outlet duct 308.

The coupling and guide system can further comprise a pair of shelves 325fixed to the support element 302 and extending parallel to the axes ofthe terminal segments 319 and 320 of the connection ducts 317 and 318,which are suitable to receive, for rest, said lateral edges 324 of theplate 323 (see also FIG. 32).

Thanks to the coupling between the plate 323 and the shelves 325, thefiltering group 301 can therefore be easily brought into an operatingconfiguration, in which the terminal segments 313 and 315 of the inletduct 307 and of the outlet duct 308 are coaxially coupled respectivelywith the terminal segment 319 of the first connection duct 317 and withthe terminal segment 320 of the second connection duct 318, asillustrated in FIGS. 30 and 31.

To selectively lock the filtering group 301 in this operating position,the filtering device 300 can comprise a suitable releasable lockingsystem.

Said releasable locking system can comprise a tightening element 326that can be slidably coupled to the support element 302 according to thesame sliding direction as the filtering group 301, after the latter hasbeen brought into the operating position.

For example, the tightening element 326 can be shaped as a coveringcase, which is suitable to be inserted like a drawer on a box-like frame327 which is fixed to the support element 302 and which is suitable tocontain the terminal segments 319 and 320 of the connection ducts 317and 318, as well as the shelves 325.

The box-like frame 327 can be shaped as a C-section profile and axisparallel to the axes of the terminal segments 319 and 320 of theconnection ducts 317 and 318, which has for example an upper flat wall328, which surmounts said terminal segments 319 and 320, and two flatlateral walls 329, which extend downwards from said upper wall 328 buton opposite sides of the terminal segments 319 and 320 themselves.

An axial end of said box-like frame 327 is open so as to allow theinsertion of the filtering group 301.

The tightening element 326 is inserted onto the box-like frame 327 andhas a rear wall 331 suitable to close the open axial end of the box-likeframe 327, opposing the terminal segments 319 and 320 of the connectionducts 317 and 318.

The tightening element 326 is also provided with one or more releasablesnap-fitting members 332, which are suitable to lock the tighteningelement 326 on the box-like frame 327 of the support element 302 in apredetermined stop position.

For example, said snap-fitting members 332 can be positioned on twolateral flanks of the tightening element 326, which are suitable tocover the lateral walls 329 of the box-like frame 327, and can besingularly configured to snap into a corresponding seat 333 obtained insaid lateral walls 329.

In particular, the hooking between the snap-fitting members 332 and thecorresponding seats 333 can take place simply by pushing the tighteningelement 326 to make it slide on the box-like frame 327, for examplethanks to a suitable conformation of the aforesaid snap-fitting members332 (for example with sawtooth shape) which allows them, following theaforesaid movement, to deform and then to snap into the relative seat333.

The tightening element 326 also has at least one abutment surface 334which, when the filtering group 301 is in the operating position and thetightening element 326 is in the stop position, is suitable to stay incontact with a corresponding abutment surface of the filtering group 301on the opposite side with respect to the terminal segments 319 and 320of the connection ducts 317 and 318 with respect to the slidingdirection, thus locking the filtering group 301 in the operatingposition.

As illustrated in FIGS. 26 and 27, in this embodiment, the abutmentsurface 334 is made available for example by a shelf 336 deriving fromthe inner surface of the rear wall 331 of the tightening element 326,while the corresponding abutment surface is made available by one ormore ribs which rise from the cover 304 of the filtering group 301 andwhich support the plate 323 (see also FIGS. 33 and 34).

Thanks to the solution described above, in order to remove the filteringgroup 301 it is then sufficient to release the snap-fitting members 332and remove first the tightening element 326 and then the filtering group301.

For this purpose, a button 337 can be associated with each snap-fittingmember 332, which is suitable to be pressed to release the hookingproduced by the snap-fitting member 332 itself.

In particular, the snap-fitting member 332 and the relative button 337can be made as a single object.

It is wished to highlight that the buttons 337 must be pressed only whenit is necessary to remove the tightening element 326 since, aspreviously anticipated, during the coupling step, the hooking betweenthe snap-fitting members 332 and the corresponding seats 333 can takeplace simply by pushing the tightening element 326 to make it to slideon the box-like frame 327.

If the filtering device 300 described above is located inside the plant100, as illustrated for example in FIG. 1, the first connection duct 317of the support element 302 can be stably connected with the outlet 203of the pump 201, while the second connection duct 318 can be stablyconnected with the first connection duct 431 of one of the modularelements 401 (see also FIG. 2).

If, on the other hand, the filtering device 300 is separated, asillustrated for example in FIG. 24, the first connection duct 317 of thesupport element 302 can be directly connected with the water network,while the second connection duct 318 can be connected with the inletduct 101 of the plant 100 or, more generally, with any utility that mustreceive the water filtered by the filtering device 300.

In this second case, it is further provided that, a non-return valve,indicated respectively with 338 and 339 (see FIGS. 26 and 27) can beinserted inside each terminal segment 319 and 320 of the connectionducts 317 and 318.

Said non-return valves 338 and 339 have the function of automaticallypreventing the water from outflowing from the water network, when thefiltering unit 301 is removed.

Therefore, both non-return valves 338 and 339 are configured so as to beclosed in the same direction, i.e. moving towards the end of therespective terminal segment 319 and 320.

In this way, both non-return valves 338 and 339 prevent water fromoutflowing from the respective terminal segment 319 and 320.

However, since the non-return valve 338 is placed on the firstconnection duct 317 (from which the water to be filtered comes from),when the filtering group 301 is repositioned it is necessary to reopenthe non-return valve 338 in contrast to the action of water.

To do this, the terminal segment 319 of the first connection duct 317can contain a presser element 340, shaped for example as a sort ofneedle, which, following the insertion of the terminal segment 313 ofthe inlet duct 307, is pushed by said terminal segment 313 and in turnpushes the non-return valve 338 into the opening position.

This presser element 340 is not present in the terminal segment 320 ofthe second connection duct 318, since the non-return valve 339 opensautomatically by effect of the exiting water flow.

Outlet Module

With particular reference to FIGS. 20 and 21, the outlet module 600first of all comprises the outlet duct 102, which preferably extendsrectilinearly along a predetermined central axis H.

At one axial end, the outlet duct 102 has a terminal segment 106, whichis suitable to be connected with one or more utilities of the treatedwater, for example but not necessarily through a manual or automaticdelivery valve (not shown).

The outlet module 600 also comprises an inlet fitting 601, which issuitable to receive the water filtered by the reverse osmosis filteringdevice 400 and to convey it towards the outlet duct 102, preferably atthe axial end opposite the terminal segment 106.

As illustrated in FIG. 8A, the inlet fitting 601 can comprise a firstsegment 602 which defines a coupling sleeve suitable for being coaxiallyinserted, by interposition of suitable sealing rings, directly insidethe outlet mouth 427 of one of the modular elements 401 of the reverseosmosis filtering device 400.

The first segment 602 of the inlet fitting 601 can be axially locked tothe outlet mouth 427 by means of a simple removable clip 651 which isinserted laterally on two opposed flanges obtained respectively aroundthe first segment 602 of the inlet fitting 601 and around the outletmouth 427 of the modular element 401.

The inlet fitting 601 may further comprise a second segment 603, whichis suitable to hydraulically connect the first segment 602 with theoutlet duct 102.

This second segment 603 can be coaxial to the outlet duct 102 and can beorthogonal to the first segment 602, giving the inlet fitting 601substantially the shape of an elbow.

Between the second segment 603 of the inlet fitting 601 and the outletduct 102, the outlet module 600 comprises a flow rate transducer 604.

The flow rate transducer 604 generally comprises an outer casingsuitable to contain an impeller 605.

In detail, the outer casing of the flow rate transducer 604 can comprisea cylindrical tang 606, which has a first axial end placed in hydrauliccommunication with the inlet fitting 601.

For example, the cylindrical tang 606 can be coaxial to the secondsegment 603 of the inlet fitting 601 and can optionally be connectedthereto by means of a truncoconical segment 607.

The outer casing of the flow rate transducer 604 can also comprise acover 608, which is suitable to close the second and opposite axial endof the cylindrical tang 606 and is provided with at least one internalthrough aperture (not visible in the figures) suitable for placing inhydraulic communication the internal volume of the cylindrical tang 606with the outlet duct 102.

In particular, the cover 608 can comprise an annular tang 609 which, byinterposition of suitable annular sealing gaskets, is inserted coaxiallyonto the cylindrical tang 606.

The gaskets are preferably housed in corresponding annular seats 610obtained on the outer surface of the cylindrical tang 606.

According to one aspect of the invention, the cover 608, with theeventual annular tang 609, is part of a first monolithic body, globallyindicated with 611, which also comprises (defines) the outlet duct 102.

Similarly, the cylindrical tang 606 is preferably part of a secondmonolithic body, globally indicated with 612, which also comprises(defines) the inlet fitting 601, including the first segment 602, thesecond segment 603 and possibly the truncoconical segment 607.

Said first and second monolithic body 611 and 612 can be made of plasticmaterial, for example by injection molding. In particular, each of saidfirst and second monolithic body 611 and 612 can be directly obtained asa single piece, or it can be obtained in several parts which are theninseparably joined together, for example by welding or gluing, thusforming a single piece.

After the first and the second monolithic body 611 and 612 have beenassembled together, by inserting the annular tang 609 onto thecylindrical tang 606, they can be mutually fixed by any conventionalsystem.

As illustrated in FIG. 21, in the embodiment in question, this fixing ismade possible by the fact that the second monolithic body 612 comprisesa flat flange 613, which is obtained between the truncoconical segment607 and the cylindrical tang 606 and is suitable to face the cover 608of the first monolithic body 611.

The flat flange 613 comprises a plurality of through holes 614, each ofwhich is suitable to be aligned with a corresponding sleeve 615 derivingin a single body from the cover 608.

In this way, the fixing between the first and the second monolithic body611 and 612 can be obtained simply with the aid of a plurality ofself-tapping screws (not shown), each of which can be inserted into arespective through hole 614 and screwed into the corresponding sleeve615.

Before the first and the second monolithic body 611 and 612 are joinedtogether, a support disc 616 provided with a central hub 617 and with aplurality of through apertures for the free outflow of water can becoaxially accommodated inside the cylindrical tang 606.

The impeller 605, which is free to rotate, by effect of the water intransit, around its own axis coinciding with the axis of the cylindricaltang 606 is also rotatably accommodated inside the cylindrical tang 606.

For example, the impeller 605 can be rotatably coupled, by means of acentral pin 618, the opposite ends of which are respectively inserted inthe central hub 617 of the support disc 616 and in a hole obtainedcentrally in the cover 608 (see FIG. 8A).

Although in the example illustrated the impeller 605 is positionedcoaxially inside the cylindrical tang 606, it is not excluded that, inother embodiments, the positioning of the impeller may be different.

The flow rate transducer 604 further comprises a system suitable fordetecting the rotation speed of the impeller 605.

Said detection system can comprise one or more reference elements 619(see FIG. 8A) fixed in an eccentric position on the impeller 605 and aproximity sensor 620, installed in a fixed position with respect to theimpeller 605, which is suitable to generate an electrical signal wheneach of said reference elements 619 passes close to the proximity sensor620 itself.

For example, the reference elements 619 can be magnetic bodies and theproximity sensor 620 can be configured to react to the magnetic fieldgenerated by said magnetic bodies as they pass.

In the illustrated embodiment, the proximity sensor 620 can be installedin a cavity 621 of the first monolithic body 611, which is made at thecover 608 so as to remain separated from the ducts in which the waterflows, while the reference elements 619 can be positioned in order to bealigned with the proximity sensor 620 over a predetermined angularposition of the impeller 605.

The proximity sensor 620 can be electrically connected with anelectronic processing unit (not illustrated) which, based on therotation speed of the impeller 605, is able to calculate the flow rateof water flowing from the inlet fitting 601 to the outlet duct 102, forexample in order to verify the correct operation of the plant 100.

Downstream of the flow rate transducer 604 (with respect to the waterdirection), the outlet module 600 comprises at least one non-returnvalve 622 (see FIG. 8A), which is installed inside the outlet duct 102so as to intercept all the water flowing inside it.

This non-return valve 622 is suitable to allow the passage of waterflowing from the inlet fitting 601 towards the outlet duct 102,preventing reverse flow.

In this way, when the utility connected to the outlet duct 102 stopsrequesting water, for example following the closure of the deliveryvalve, a water hammer is generated which automatically closes thenon-return valve 622, keeping an intermediate segment of the outlet duct102 comprised between the terminal segment 106 and the non-return valve622 itself under pressure.

When the utility requests water again, for example following thereopening of the delivery valve, the pressure in said intermediatesegment of the outlet duct 102 drops rapidly, allowing the opening ofthe non-return valve 622 and therefore a new inflow of filtered water.

To make this operation safer, the outlet module 600 can comprise atleast one further non-return valve 623, which is completely similar tothe previous one and is inserted inside the outlet duct 102, upstream ofthe non-return valve. 622 with respect to the direction of the wateroutflow.

The outlet module 600 can comprise a locking element 624, which is fixedto the outlet duct 102 at the terminal segment 106 and, protrudinginside the outlet duct 102 itself without obstructing it, contacts thenon-return valve 622, locking it axially and preventing it from slippingoff.

Returning to FIGS. 20 and 21, the first monolithic body 611 of theoutlet module 600 can further comprise a secondary duct 625, whichderives from and is in hydraulic communication with the intermediatesegment of the outlet duct 102 comprised between the nonreturn valve 622and the terminal segment 106.

Said secondary duct 625, which can be straight and extend along an axisperpendicular to the axis H of the outlet duct 102, therefore has anefferent axial end in the intermediate segment of the outlet duct 102and an opposite free axial terminal end 626.

In some embodiments, such as the one illustrated in FIG. 9, the terminalend 626 of the secondary duct 625 can simply be closed with a plug.

In other embodiments, such as the one illustrated in FIG. 1, theterminal end 626 of the secondary duct 625 can be connected with theinlet duct 101 of the plant 100, by interposition of the bypass solenoidvalve 105.

In this way, if, for example, the plant 100 has a failure and the mainsolenoid valve 104 is kept constantly closed, the utilities can still besupplied with water (although it is not treated), simply by opening thebypass solenoid valve 105 which allows water coming from the waternetwork to flow directly from the inlet duct 101 into the secondary duct625 of the outlet module 600 and from there into the outlet duct 102towards the utilities.

In this case, another non-return valve 650, which is suitable tointercept all the water that flows inside the secondary duct 625, can beinterposed between the terminal end 626 of the secondary duct 625 andthe bypass solenoid valve 105.

In particular, said non-return valve 650 is suitable to allow thepassage of water flowing from the bypass solenoid valve 105 towards theoutlet duct 102, preventing reverse flow.

The first monolithic body 611 of the outlet module 600 can furthercomprise a connection port 627, which is placed in hydrauliccommunication with the intermediate segment of the outlet duct 102comprised between the non-return valve 622 and the terminal segment 106.

In the illustrated embodiment, said connection port 627 deriveslaterally from the secondary duct 625, for example from an intermediatesegment of the secondary duct 625 comprised between the outlet duct 102and the terminal end 626.

The connection port 627, which can extend with straight axis parallel tothe central axis H of the outlet duct 102, is suitable to be directlycoupled with a pressure-sensitive device 107 (see FIGS. 7 and 9), sothat the latter is suitable to detect the pressure that reigns in theintermediate segment of the outlet duct 102 comprised between thenon-return valve 622 and the terminal segment 106.

This pressure-sensitive device 107 is preferably a pressure switch whichdirectly controls the pumping group 200 and possibly also the mainsolenoid valve 104.

Alternatively, the pressure-sensitive device 107 can be a pressuretransducer 107 which can be connected to the electronic control unitwhich controls the main solenoid valve 104 and the pumping group 200.

In both cases, when the pressure-sensitive device 107 detects a pressurehigher than a predetermined threshold value, indicative for example thatthe request for water by the utilities has been interrupted, the motor204 of the pumping group 200 is automatically stopped and eventually themain solenoid valve 104 is also closed.

Conversely, when the pressure-sensitive device 107 detects that thepressure has dropped below the threshold value again, that is theutilities have been reopened and request water, the main solenoid valve104 can be automatically opened and the motor 204 of the pumping group200 is put back into operation.

The first monolithic body 611 of the outlet module 600 can furthercomprise a coupling port 628, which derives from and is placed also inhydraulic communication with the intermediate segment of the outlet duct102 comprised between the non-return valve 622 and the terminal segment106.

In the illustrated embodiment, said coupling port 628 can derivedirectly from the outlet duct 102, for example extending with axisstraight and coinciding with the axis of the secondary duct 625 but onthe opposite side of the latter.

The coupling port 628 is suitable to be directly coupled with aconductivity transducer 108 (see FIG. 7), so that the latter is suitableto detect the electrical conductivity of the water flowing along theintermediate segment of the outlet duct 102 comprised between thenon-return valve 622 and the terminal segment 106.

The conductivity transducer 108, which is known per se and conventional,can be connected to the electronic control unit, so that the latter can,for example, control the operation and the efficiency of the plant 100.

In fact, the electrical conductivity of water generally depends on theconcentration of salts dissolved therein, so that this parameter canprovide an indirect indication of the operation and of the filteringcapacity of the reverse osmosis filtering device 400.

Finally, the outlet module 600 can comprise a connecting duct 629, whichderives from and is also placed in hydraulic communication with theintermediate segment of the outlet duct 102 comprised between thenon-return valve 622 and the terminal segment 106.

This connecting duct 629 can extend with axis straight and orthogonalboth to the central axis H of the outlet duct and to the axis of thesecondary duct 625 but preferably incident with the latter into a commonintersection point.

In the example of FIG. 8A, the connecting duct 629 is closed with aplug, however, in other embodiments, it is suitable to be hydraulicallyconnected to an auxiliary device (not illustrated).

Said auxiliary device can be a tank, which is preferably positioned at ahigher level than the outlet duct 102.

This tank can effectively act as a buffer for storing the treated water,to allow a more immediate supply of the same when requested by theutilities.

In fact, as previously explained, when the utilities request water, forexample through the opening of the respective delivery valve, thepressure in the outlet duct 102 decreases and, only following pressuredecrease, the electronic control unit controls the actuation of thepumping group 200 and possibly the opening of the main solenoid valve104.

This procedure can therefore involve a certain delay between the instantin which the water is requested by the utilities and the instant inwhich the water is actually supplied.

The presence of a storage tank connected to the connecting duct 629 canmitigate this delay.

In fact, during normal operation of the plant 100, the storage tank isfilled with a part of the filtered water travelling towards theutilities connected to the outlet duct 102.

When the request for water stops, this filtered water remains confinedinside the storage tank.

When the delivery is reopened, the pressure drop in the outlet duct 102causes the filtered water stored in the tank to flow immediately towardsthe utilities, waiting for the plant 100 to return to normal operation.

Obviously, a person skilled in the art can make numerous modificationsof a technical-applicative nature to everything described above, withoutthereby departing from the scope of the invention as claimed below.

1. A modular element (401) for making reverse osmosis filtering devices(400), comprising: at least one first container (403) and a secondcontainer (404), each of which is provided with a tubular lateral wall(405), with a bottom plate (406) which closes a first axial end of saidlateral wall (405), with an inlet (408, 417), with a first outlet (409,418) and with a second outlet (410, 419), said at least one firstcontainer and second container (403, 404) being arranged so that therespective lateral walls (405) are arranged adjacent and have mutuallyparallel central axes (A, B), and a scavenging duct (423) which connectsthe second outlet (410) of the first container (403) with the inlet(417) of the second container (404), wherein said at least one firstcontainer (403), said second container (404) and said scavenging duct(423) are obtained as a single monolithic body (402).
 2. The modularelement (401) according to claim 1, wherein the first outlet (409, 418)of each of said at least one first container and second container (403,404) is obtained in the corresponding bottom plate (406), while theinlet (408, 417) and the second outlet (410, 419) of each of said atleast one first container and second container (403, 404) are obtainedin the corresponding lateral wall (405), on the side facing towards thelateral wall (405) of the other container.
 3. The modular element (401)according to claim 2, wherein the inlet (408, 417) and the second outlet(410, 419) of each of said at least one first container and secondcontainer (403, 404) have axes perpendicular to the central axes (A, B)of the lateral walls (405) of the at least one first container and ofthe second container (403, 404) and lie in the same plane on which thecentral axes (A, B) of said lateral walls (405) lie.
 4. The modularelement (401) according to claim 2, wherein the monolithic body (402)comprises two connection ducts (431, 432), which are positioned in aninterspace (407) comprised between the lateral walls (405) of the firstand of the second container (403, 404) and wherein the axes are straightand orthogonal to the plane on which the central axes (A, B) of saidlateral walls (405) lie, a first (431) of said connection ducts beingplaced in hydraulic communication with the inlet (408) of the at leastone first container (403) while a second (432) of said connection ductsbeing placed in hydraulic communication with the second outlet (419) ofthe second container (404), each of these first and second connectionduct (431, 432) have two opposite axial ends which project on oppositesides with respect to said plane on which the central axes (A, B) of thelateral walls (405) of the at least one first container and of thesecond container (403, 404) lie.
 5. The modular element (401) accordingclaim 1, wherein the monolithic body (402) comprises a collectionmanifold (426) communicating both with the first outlet (409) of the atleast one first container (403) and with the first outlet (418) of thesecond container (404) and provided with an outlet mouth (427).
 6. Themodular element (401) according to claim 5, wherein the monolithic body(402) comprises a third connection duct (433) having axis straight andorthogonal to the plane on which the central axes (A, B) of the lateralwalls (405) of the at least one first container and of the secondcontainer (403, 404), which intersects the collection manifold (426) andhas two opposite free ends projecting from opposite sides of thecollection manifold (426) lie.
 7. The modular element (401) according toclaim 5, wherein a bypass opening (428) which places the internal volumeof the at least one first container (403) in communication with thecollection manifold (426) is obtained in the bottom plate (406) of theat least one first container (403), a valve (429) being provided forclosing and/or adjusting the opening degree of said bypass opening(428).
 8. The modular element (401) according to claim 4, wherein themonolithic body (402) comprises one or more fixing bushings (442), eachof which is positioned in the interspace (407) comprised between thelateral walls (405) of the at least one first and of the secondcontainer (403, 404) and has an axis orthogonal to the plane on whichthe central axes (A, B) of said lateral walls (405) lie.
 9. The modularelement (401) according to claim 1, wherein the monolithic body (402)comprises a plurality of positioning tangs (440) deriving from thelateral walls (405) of the at least one first container and of thesecond container (403, 404) with axes perpendicular to the plane onwhich the central axis (A, B) of the lateral walls (405) lie, and aplurality of positioning pins (441) also deriving from the lateral walls(405) of the at least one first container and of the second container(403, 404), each of which is coaxial to a corresponding positioning tang(440) but it is obtained on the opposite side of the latter with respectto the plane on which the central axes (A, B) of the lateral walls (405)lie.
 10. The modular element (401) according to claim 1, wherein themonolithic body (402) comprises at least two fixing plates (444, 445)lying in the plane on which the central axes (A, B) of the lateral walls(405) of the at least one first container and of the second container(403, 404) lie, each of which derive from the lateral wall (405) of arespective container (403, 404) from the opposite side with respect tothe other container.
 11. The modular element (401) according to claim 1further comprising two osmotic membrane filtering cartridges (411, 420),each of which is inserted into a respective of said at least one firstcontainer and second container (403, 404), for partitioning the volumethereof into three chambers, including a first chamber (412, 421) placedin communication with the inlet (408, 417), a second chamber (413, 422)placed in communication with the first outlet (409, 418) and a thirdchamber (460, 461) placed in communication with the second outlet (410,419).